Titanium is neither considered essential to the growth of nor toxic to higher plants. It is insoluble in the pH range of 4-8 where plants normally grow in soil. It has been reported that potassium titanate added to solution cultures improved the growth of alfalfa. It also has been reported that titanium sulfate and potassium titanate increased the number and caused earlier formation of nodules. Titanium oxide is also believed to act as a photocatalyst in the photochemical oxidation of nitrite to nitrate. It has been reported that titanium enhances root growth. It is not believed, however, that titanium has been complexed with certain polymers to render it available to the growing plant when coated on the seed.